> except for pre-shared one time pads when used correctly

The relevant property here is known as "information-theoretic security", and I'm not sure if one-time pads are the only way to achieve it, e.g. Shamir's secret sharing also has this property (although the use case is slightly different): https://en.wikipedia.org/wiki/Information-theoretic_security

Isn’t one time pad just a simple version of secret sharing?

Those are the only two known algorithms that have this property.